HTC's flagship smartphone is the One X+, a spruced up version of the One X. Watch our HTC One X+ video review to find out what's changed.

At a glance, the One X+ looks identical to the One X. That's because HTC has only made changes inside, so the handset is just 8.9mm thin and weighs 135g.

They may look the same but we found the already good build quality of the One X to be even better in the One X+. The worrying ripple effect of the screen which occurred if the handset was squeezed along the side doesn't happen on the updated model.

The One X+ still has 1Gig of RAM but packs a faster nVidia Tegra 3 processor. It's only a jump to 1.7GHz from the One X's 1.5GHz chip but we saw a big jump in benchmark results.

A score of 1529 in Geekbench 2 was a much bigger increase in performance than the 27 percent touted by HTC.

There's still no microSD slot, but the One X+ has a generous 64Gig of internal storage as standard - three times the amount of the Samsung Galaxy S3, which costs about the same.

The screen is also unchanged from the One X, which is no bad thing. The 4.7in Super IPS display has such a high pixel density it gives the illusion that you're looking at a glossy printed page instead of a screen.

Like all of HTC's phones, the One X+ comes with Beats Audio. Really, this does nothing more than pump up the volume and bass unnecessarily.

The operating system is Android 4.1 Jelly Bean but HTC adds its Sense 4+ overlay to the interface.

There are certain elements missing such as the two-finger pull down quick settings bar and no option to put widgets on the lock screen. HTC does have a selection of lockscreen designs that show information and a top-quality widget library. We're pleased that HTC didn't rid of Google Now.

HTC has given the recent apps part of Android a 3D view. Although this isn't necessary it looks good and we like the fact yo u can choose to use the recent apps button below the screen to bring up menus when you hold it down.

Thanks to its upgraded battery, we comfortably managed to get two days of use from the One X+. The higher capacity is helped out by a handy power saving mode.

With a newer version of Android, no build quality issues and significantly better battery life, the One X+ is a polished and honed version of its predecessor.

It's now an even better all-round smartphone at a reasonable price, too.